Characterization of Particle Movement and High-Resolution Separation of Microalgal Cells via Induced-Charge Electroosmotic Advective Spiral Flow

Abstract

Microalgae are renewable, sustainable, and economical sources of biofuels and are capable of addressing pressing global demand for energy security. However, two challenging issues to produce high-level biofuels are to separate promising algal strains and protect biofuels from contamination of undesired bacteria, which rely on an economical and high-resolution separation technology. Separation technology based on induced-charge electroosmotic (ICEO) vortices offers excellent promise in economical microalga separation for producing biofuels because of its reconfigurable and flexible profiles and sensitive and precise selectivity. In this work, a practical ICEO vortex device is developed to facilitate high-resolution isolation of rich-lipid microalgae for the first time. We investigate electrokinetic equilibrium states of particles and particle-fluid ICEO effect in binary-particle manipulation. Nanoparticle separation is performed to demonstrate the feasibility and resolution of this device, yielding clear separation. Afterward, we leverage this technology in isolation of Chlorella vulgaris from heterogeneous microalgae with the purity exceeding 96.4%. Besides, this platform is successfully engineered for the extraction of single-cell Oocystis sp., obtaining the purity surpassing 95.2%. Moreover, with modulating parameters, we isolate desired-cell-number Oocystis sp. enabling us to investigate proliferation mode and carry out transcriptome analyses of Oocystis sp. for high-quality neutral lipids. This platform can be extended directly to economically separate other biological micro/nanosamples to address pressing issues, involving energy security, environmental monitoring, and disease diagnosis.

Dielectric Characterization and Multistage Separation of Various Cells via Dielectrophoresis in a Bipolar Electrode Arrayed Device

“…Other fabrication details are given in our previous reports. 34 Experimental Setup. Separation devices were mounted on the optical microscope (BX53, Olympus, Japan) with a highspeed camera (RETIGA2000R, Qimaging, Canada), through which we can investigate and image the movement of cells in the platform.…”

“…KCl solution buffer with σ = 0.2, 1, 10, 50, and 100 mS/ m was prepared to test the dielectric responses of cells. 34 To obtain pure cells, cells were put in the tubes to conduct centrifugal treatment for 3 mins, and culture mediums were then replaced by separation buffers. This procedure was repeated for six times.…”

“…Moreover, due to a large channel layout, Sylgard 184 Silicone Elastomer Base and Curing Agent (Dow Corning, USA) were mixed in a weight ratio of 4:1 to eliminate channel deformation after peeling from the mold. Other fabrication details are given in our previous reports …”

“…To avoid aggregation of microalgae, we used the low-conductivity KCl solution as the buffer. KCl solution buffer with σ = 0.2, 1, 10, 50, and 100 mS/m was prepared to test the dielectric responses of cells . To obtain pure cells, cells were put in the tubes to conduct centrifugal treatment for 3 mins, and culture mediums were then replaced by separation buffers.…”

Review of nonlinear electrokinetic flows in insulator‐based dielectrophoresis: From induced charge to Joule heating effects

“…More studies are needed to understand accurately the interplay of ICEO and electrothermal flows, which will aid the optimal design and operation of future iDEP microdevices. More applications are expected on the way for ICEO (e.g., [157][158][159]) and electrothermal [160][161][162][163][164][165] flows that are not necessarily limited to iDEP microdevices. To move forward, there are some research directions in the field, which, from this author's view, may be worthy of further investigations and are outlined below.…”